Salaah with Jamaat
Besides the great virtues mentioned in the Ahadith of performing Salaah in Jamaat, there are two great benefits in performing Salaah in congregation.

Concentration – By nature, the environment we are in will always affect us. When others around us are doing something, it becomes easier for us to do the same. This is why fasting is easier in Ramadaan than in any other month even though Ramadaan might fall in the summer months. When we perform Salaah in Jamaat, it becomes easier to concentrate in Salaah. This is because everyone around us is silent and engrossed in their Salaah. Compare this to performing Salaah at home where the kids might be making noise or the phone might be ringing while you are performing Salaah.

Forgiveness – Allah loves when His servants worship Him collectively. For this reason, Hajj is at one specific time of the year. When Allah is happy with us, He is willing to forgive. When we perform Salaah in Jamaat, there is hope that our shortcomings in Salaah will be overlooked and forgiven by Allah due to the blessings of congregation.

Incident of Sahaaba
The importance of Salaah with Jamaat is well established from Ahadith of Nabi S.A.W. Even after the demise of Nabi S.A.W., the Khalifas were very particular about the males performing Salaah with Jamaat. There is an incident regarding Umar R.A…
On one occasion, Umar R.A. noticed that Sulaimaan bin Abi Hathmah R.A. was not in the Masjid for the Fajr Salaah. Umar R.A. thereafter proceeded to the market, and since the home of Sulaimaan R.A. was between the Masjid and the market, Umar R.A. stopped at his home and asked his mother… “Why did I not see Sulaimaan for the Fajr Salaah today?” She replied, “He spent the entire night performing Nafl Salaah. Hence, he fell asleep at the time of Fajr and was unable to awaken.” Hearing this, Umar R.A. remarked, “Performing Fajr Salaah with Jamaat is more beloved to me than performing Nafl Salaah the entire night.”

Incident of the pious
There is another incident from the lives of the pius that shows how much importance they attached to Salaah with Jamaat…
Maimoon bin Mahraan R.A. once arrived at the Masjid, only to be informed that the people had already departed (as the Salaah was over). Hearing this, he recited, “Innaa lillaahi wa innaa ilaihi raaji‟oon,” and then said, “The reward of performing this Salaah with Jamaat is more beloved to me than being appointed as governor of Iraq.